Leasing Arrangements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Leases [Abstract]
Capital Lease Obligations	$ 12,000
Operating lease term maximum (in years)	25 years
Operating lease expense	$ 9,300	$ 8,600	$ 8,300
Capital Leases
2018	2,172
2019	2,172
2020	2,172
2021	2,172
2022	2,172
2023 and thereafter	22,609
Total minimum lease payments	33,469
Amounts representing interest	20,661
Present value of net minimum lease payments	12,808
Operating Leases
2018	8,096
2019	6,297
2020	5,471
2021	4,605
2022	5,636
2023 and thereafter	3,281
Total minimum lease payments	$ 33,386